A collinear model for small-x physics
M. Ciafaloni, D. Colferai, G. P. Salam
TL;DR
The paper introduces a collinear model for small-x physics that retains only the collinearly enhanced components of the leading and subleading kernels, while incorporating the full one-loop running coupling. This model reduces the small-x equation to a second-order differential equation in the logarithmic momentum variable and is analyzed analytically and numerically to explore both perturbative and strong-coupling regimes. For two-scale processes, it clarifies the transition between the perturbative, non-Regge regime and the strong-coupling Pomeron behavior. The approach provides a simple, solvable framework that captures key qualitative features of BFKL-like dynamics with RG improvements and collinear physics.
Abstract
We propose a simple model for studying small-x physics in which we take only the collinearly enhanced part of leading and subleading kernels, for all possible transverse momentum orderings. The small-x equation reduces to a second order differential equation in t=log k^2/Lambda^2 space, whose perturbative and strong-coupling features are investigated both analytically and numerically. For two-scale processes, we clarify the transition mechanism between the perturbative, non Regge regime and the strong-coupling Pomeron behavior.